metal chimney height

Anyone able to tell me what the maximum height is for an unsupported 8" metal chimney. Also, not really the right forum but since I’m here… Dosen’t an 8" round chimney opening seem a bit small for a pre fab wood burning fireplace. I’m thinking this might have been designed for a gas log set not wood burning. Is there a min. opening for a wood burning fp?

RE: chimney diameter, from a quick IRC lookup (M1805.3 and M1805.3.1), it looks like it can’t be smaller than the connector at the fireplace/appliance. So if the connector at the top of the fireplace is 8", then 8" all the way up would be ok.

Here, it is higher than two sections of pipe.

Size is IAW Mfg install requirements. Too big of a pipe may not have sufficient draw to properly vent the appliance. So bigger may not always be better.

I believe the maximun height of unguyed chimney above the roof is 5 feet, if that’s what you’re asking.

Yes, I thought 6’, either way at 7’ it’s too tall to be unguyed.
The other question is this; the fireplace is a prefab, much like I’ve seen in condos, open hearth with gas log set, it’s got a firebrick veneer and a metal top with a round 8" damper going into metal duct/chimney. Is this ok for wood burning? I thought a wood burning fireplace usually had a larger opening, smoke shelf, etc. Seems like the amount of smoke and heat from a wood burning fireplace could overwhelm that flat top and 8" damper.
My concern ios that they have taken what was meant to be a prefab fp for a gas log set and made it into a wood burning fp.

From your description it sounds like a standard Metal prefab fireplace. In our part of the country where everyone thinks they want a wood burning FP in their home this particular type of FP is very common. The majority of them are made by Marco and they do burn wood in them. Ive seen many that have been converted to a gas log set once the owners figured out a small wood burning FP is more work than it is worth. You actually generate more heat just cutting the wood than the actual fire does.

You are right to have the concern. It is best to see the manufacturer’s installation/use instructions to determine usage…otherwise, if it appears modified, I’d state that and defer it to a qualified professional.

Thanks guys.

Where in the IRC is this information listed. I have looked and cannot find it. I inspected a home today that had an unsupported 8 foot metal flue.

Here you go: